Dentin is the substance between enamel or cementum and the pulp chamber. It is secreted by the odontoblasts of the dental pulp. The formation of dentin is known as dentinogenesis. The porous, yellow-hued material is made up of 70% inorganic materials, 20% organic materials, and 10% water by weight.
Medical Definition of metaplasia. 1  1: transformation of one tissue into another metaplasia of cartilage into bone. 2  2: abnormal replacement of cells of one type by cells of another.
Apocrine metaplasia is sometimes described as a âbenign epithelial alterationâ of breast tissue, which means that epithelial cells are undergoing an unexpected change. The word apocrine means something to do with sweat, but only a resemblance. Itâs not actually sweat gland related.pocrine metaplasia is a â non-proliferative â breast lesion, and is usually associated with breast fibrocystic disease. The term âproliferativeâ would mean that cells are growing and growing, and in a somewhat unpredictable way. Proliferative cells growth is therefore usually associated with carcinoma.